Interpretive Handbook

Test
62512 :
Small Lymphocytic Lymphoma, FISH, Tissue

Small lymphocytic lymphoma (SLL) is the non-leukemic form of chronic lymphocytic leukemia (CLL), the most common adult leukemia in North America. The most common cytogenetic abnormalities detected in CLL are deletions of 6q, 11q, 13q and 17p, trisomy 12 and the occasional occurrence of IGH translocations at 14q32. Cytogenetics has proven to be a reliable predictor of outcome for patients with CLL. It is unknown if SLL has the same prognostic significance when these genetic abnormalities are observed.

This fluorescence in situ hybridization test detects an abnormal clone in approximately 65% of patients with SLL. Patients with t(11;14)(q13;q32) associated with CCND1/IGH fusion, have mantle cell lymphoma which can be distinguished from SLL and other B-cell lymphomas with this assay. Patients with t(14;18)(q32;q21) or t(14;19)(q32;q13.3) may have an atypical form of SLL or another low-grade B-cell lymphoma.

This test is not approved by the FDA, and it is best used as an adjunct to existing clinical and pathologic information.

Fixatives other than formalin (eg, Prefer, Bouin) may not be successful for fluorescence in situ hybridization (FISH) assays. Although FISH testing will not be rejected due to nonformalin fixation, results may be compromised.

Paraffin-embedded tissues that have been decalcified are generally unsuccessful for FISH analysis. The pathologist reviewing the hematoxylin and eosin-stained slide may find it necessary to cancel testing.